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xfstests, weird looking code in src/resvtest.c

To: xfs@xxxxxxxxxxx
Subject: xfstests, weird looking code in src/resvtest.c
From: scameron@xxxxxxxxxxxxxxxxxx
Date: Tue, 17 Jun 2014 11:20:44 -0500
Cc: scameron@xxxxxxxxxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
User-agent: Mutt/
This code in xfstests src/resvtest.c looks pretty strange:

 32         char            *readbuffer, *writebuffer;
 70         readbuffer = memalign(psize, bsize);
 71         writebuffer = memalign(psize, bsize);
 72         if (!readbuffer || !writebuffer) {
 73                 perror("open");
 74                 exit(1);
 75         }
 76         memset(writebuffer, 'A', sizeof(writebuffer));

^^^ writebuffer is a pointer, so using sizeof(writebuffer) here is
odd. Is it intentional to put either 4 or 8 A's into writebuffer
depending on sizeof a pointer?  Seems unlikely.

110         while (++n < iterations) {
111                 char *p;
112                 int numerrors;
114                 if (write(writefd, writebuffer, sizeof(writebuffer)) < 0) {
115                         perror("write");
116                         exit(1);
117                 }

So that write will write sizeof a pointer's worth of whatever's in writebuffer.
Intentional?  Again, seems unlikely.

This seems like maybe somebody initially declared writebuffer as an array, but
later went back and changed it to a pointer, but forgot to fixup everywhere that
referred to sizeof(writebuffer).

I would have sent a patch but I'm not sure what this code is trying to do.

gcc 4.4.7 (what comes with RHEL6u5) doesn't warn about this, but 4.8.3 does.

-- steve

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